1. Technical Field
The present invention relates to a semiconductor integrated circuit and a method for driving the same, and more particularly, to a phase change memory apparatus having a global bit line and a method for driving the same.
2. Related Art
In general, a semiconductor memory apparatus has a number of different operation modes. These operation modes include a standby mode, an active mode, and a deep power down mode. The standby mode refers to a state in which no chip is selected. The active mode refers to a state in which the read and write operations inherent to the semiconductor memory apparatus can be performed in response to the application of commands. In the standby and active modes, the semiconductor memory apparatus has the same internal voltage levels.
In the deep power down mode, the internal voltages under the standby and active modes are dropped or intercepted, so that circuits operating by the internal voltages are interrupted and the current consumed by an internal voltage generation circuit including a level boosting or level dropping circuit comes down to zero.
A phase change memory apparatus as a next-generation memory apparatus also has a standby mode, an active mode, and a deep power down mode. When entering the deep power down mode, internal power is intercepted so that cell data write current supplied from bit lines is intercepted.
When such a phase change memory apparatus operates in the deep power down mode, since internal voltages are intercepted at the same time with the application of a command for entering the deep power down mode, the discharge of the bit lines cannot be smoothly implemented.
That is to say, when entering the deep power down mode, since the internal voltages are intercepted at the same time with the discharge of global bit lines, a time for discharging the global bit lines is extended, and it is difficult to protect the cell data of the bit lines connected to the global bit lines. Due to this fact, a problem can be caused in terms of latch-up, and a power-up time for returning to a normal operation cannot help but be lengthened.